Prospects for Fiber to the Home (FTTH)

 

The briefing was prepared by Raj Reddy ( rr@cmu.edu ) for use by PITAC based on the material provided by Paul Shumate, Executive Director of Broad Band Local Access and Premises Network at Bellcore. ( pws@bellcore.com )

 

Fiber to home has always been an attractive option. It has all the benefits of the fiber. It provides a future-proof network in that we do not have to go through the hassles of upgrading from ADSL to XDSL to digital co-ax to digital wireless. It does not have to contend with Electro Magnetic Interference problems. No outside plant actives(?) implies highest reliability. It does not need electric powering and is immune to lightning and other transients. These properties of the fiber lead to lowest powering costs and lowest operational costs (such as maintenance, provisioning and facilities planning).

 

There has been significant and continuing progress in the area of fiber to home. In the eighties, FTTH was considered impractical because it was too expensive, incompatible with analog TVs, bandwidth needed for digital TV was too high since standards, such as MPEG II, were not in place yet. Further, there were issues of lifeline(?) covering and lack of product standardization.

 

Recent advances in Passive Optical Networks, Loop Lasers, fiber and other components, and chips for compressing Digital Video reduce the system costs down by a factor of 3 to 4 (more detail?). Digital TV standards have been announced recently by FCC. The HD 0 Broadcasting is expected to commence by end of 1998. There is an opportunity for data to be piggy back on the digital TV broadcast channel (for further information, see www.dtv.org ). The Full Service Access Network (FSAN Initiative) promises international standards on fast track. The telecom deregulation permits new players to enter the market.

 

Several new technologies are leading to cost reduction of FTTH. Until 1988, a single fiber was needed to connect to each home separately. Recent advances permit N-way distribution of the bits to many homes through resource sharing circuits (Passive Optical Network based FTTH). The Loop Laser Technology has advanced from simple stable coaxial laser packages derived from CD technology in 1986 to all plastic, all passive alignment, standard DIL packages in 1996. These devices operate in a wide range of temperatures from -40 to +85 C and do not require any pre bias, feed back control or TE Cooler. The reliability and stability of these devices appears to exceed 100 kh @ 85C.

 

The installed first cost of FTTH is greater for loop lengths of under 40,000 feet than FTTC, whereas it costs less over those distances (Why? Need further detail). Although the installed first cost premium of the FTTH is in the range of $200 to $500 over the FTTC, these costs are often offset completely by the life cycle cost reductions resulting from reduced cost of external maintenance, drop maintenance, and electric powering costs of FTTH.

 

For Rural Access Networks, assuming 10 homes per mile with 95% POTS (plain old telephone service) penetration, the installed first cost of broad band FTTH is expected to be lower than other proposed solutions such as broad band FTTC (Fiber to the Curb), DLC/ADSL(Digital Loop Carrier/Asymmetric Digital Subscriber Line) and NBDLC ( Narrow Band Digital Loop Carrier). This has led Dorman, CEO of Pacific Bell, to state, "By 2000, fiber all the way to home will be used to replace local loop routinely". E. Langenberg, Consultant, said in May, 1997, "FTTH is already cost competitive with many newbuild HFC (Hybrid Fiber/Coax) scenarios…. It is likely that FTTH will be cost-competitive with the average, as well as the high-end versions, of HFC sometime next year."

 

Although the US Telecom providers have been largely inactive in the FTTH arena, there has been substantial interest around the world. The FSAN initiative (Full Service Access Network) has a large number of operators and suppliers, the "who is who" from around the world, participating. The recent FSAN Conference in Atlanta, GA in March 1997 released key FSAN Specs. These are compatible with all current and future services. The proposed FTTx architectures operate at OC3 or OC12 rates, using 1 to 16 way or 1 to 32 way branching ATM PONs (Passive Optical Networks), and VDSL for the last connection to customer unless the customer has FTTH. The standards use a TMN (Telecommunications Management Network) compliant operations support system.

 

In summary, FTTH has all the makings of the surviving technology for the 21st century. It has all-fiber-plant, future-proof bandwidth potential, low powering and operations cost, leading to cost parity in rural areas now. As costs continue to fall, the suburban and then urban installations will also reach parity, especially, if you take into account the life cycle cost. International operators and suppliers are forging ahead with the FSAN initiative to create internationally agreed upon specs and standards, with or without US involvement.

In conclusion FTTH is the best option today for the last mile connection and makes sense as the best short term and long-term option.

 

References

 

P.W. Shumate, " What is Happening in Fiber-to-the-Home? ", Invited Paper Presented at the Conference on Lasers and Electro-Optics, CLEO'97, Baltimore, May 21,1997, CWJ-1

 

R. C. Menendez et al. " Cost comparisons of FTTC and FTTH for various Demands and Densities", VIII Intl Workshop on Optical/Hybrid Access Networks, Atlanta, Ga. March 2, 1997.